Electric circuit controller



April 11, 1944- G. R. TowNsl-:ND L:a1-Al. 2,346,520

ELECTRIC CIRCUIT CONTROLLER Filed Feb. 17, 1943 Inventors: George RTowns'end, Chester I Hall,

Their Attorney.

Haunted Apr. il, i944 .1. Hall, Wischers Ferry, N. Y., assig'nors to Gen- Ieral Electric Company,

York

a corporation of New 'Application schmal-y 17,1943, serial No. 476,202

' (ci. zoo-11m '7 Claims.

Oui' invention relates to electric circuit controllers. and more particularly to thermal responsive electric switches of the general type disclosed in Patent 1,527,645-.Hall for effecting the interruption of an electric circuit in response to a sustained abnormal current.

It is a general object of our invention to produce a new and improved thermal overload switch of the above character which shall be of simple and rugged construction, inexpensive to manuacture, and durable, reliable and accurate in operation. n n

It is a further object of our invention to provide a new and improved thermal overload relay which shall be insensitive to vibration and to severe impact. Y

It is a still further object of our invention to provide a new and improved means for' accurately calibre-ting an electric circuitl controller of the thermal latch type.

y provide a pair of cooperating switch contacts arranged either directly or indirectly to control the current in an electric circuit to be protected. To effect suitable controlling movement of the contacts in response to an abnormal current in the circuit, we provide a thermally expansible ele ment xedly mounted at one end and connected at its other end to a pivoted datent lever. The detent lever is connected for continuous following engagement with the movable end of the thermal member by providing little, or substantially no, lost motion in the connection therebetween. A switch actuating member is arranged normally to be held in a latched position bythe detent lever and is plvotally mounted upon a double eccentric pivot having a multiplicity of adjustments for controlling -the position 4of the switch actuating member' in lits latched position with respect to the detent lever. By movement of the latched member relative to the detent lever, it is possible to determine the position ofV the latch lever, and hence the temperature of the thermal responsive member, at which release oi the switch actuating. member is effected.

Our invention itselt'will be more fully understood by referring now to the. following detailed speciilcation taken in conjunction with the ac companying drawing in which `Fig. 1 is a front view of a thermal overload relay embodying my invention; Fig. 2 is a `cross-sectional view ofthe relay of Fig. l. taken along the line 2--2 of Fig. l; Fig. 3 is a front view similar to Fig. l showing one of the thermal responsive assemblies in its tripped position; and Fig. 4 is an exploded perspective view of the doubly adjustable pivot means for the switch actuating member.

Referring now to the drawing, we have shown a preferred embodiment of our invention in the ionn of a thermal responsive electric switch suitable for the protection of a three-phase electric circuit in the manner .described in connection with Fig. 3 of the above-identified patent to Hall. The relay comprises a pair of thermal responsive assemblies iii and iI mounted within an insulating casing i2 for joint cooperation with a pair of cantilever spring contacts i3 and i4 which are connected respectively to a pair of switch terminals i3d and Ha upon the top of the casing i2.

The switch contacts I3 and. i4 are biased into engagement. The thermal assembly Ii] is arranged to actuate the switch Contact I4 to a circuit interrupting position and the thermal assembly ii is arranged to actuate the switch contact i3 to a circuit interrupting position. The thermal assemblies are disposed in juxtaposition onopposite sides of the casing I2 for joint oooperation with the contacts I3 and I4 in the manner described. Since the assemblies Ill and II are o similar construction, only one will bev described ln detail.

Referring now more particularly to the thermal assembly it, this unit comprises a box-like base I5 attached to the back of the casing i2 by bolts I6 and il and having an upper end wall i3 for supporting' a hollow tube I Q of thermally expansible material, such as nickel or a special alloy having a high coeiiicient of expansion. The base l5 is also provided with a side and front wall 20 partially enclosing the tube I9. The thermally expansible tube i9 is arranged to be heated by a hairpin shaped heater 2l extending through the top ci the casing i2 'into the tube I9 and having its ends connected to a pair of heater terminals 22 and 23 mounted externally of the casing I2. Y

At the lower end of-the base plate I5 a detent lever 24 is pivotally mounted upon a pin 25 extending between the front and rear walls of the base plate l5. The detentlever 24 is connected intermediate'its ends to the lower or movable end of the thermally expansible tube I9. In the form of the invention shown in the drawing, the connection ofthe tube I9 to the deient lever 24 is made by cutting away. one-half o the periph-y ery of the tube for.v a.l portion oi itsfllength at the lower end and slotting the remaining half of the tube I9. the detent lever 24 passing through the slot in the tube. Preferably, the length of the slot in the lower end of the tube I9 is suicient to permit insertion of the lever 24 and a torsion spring (not shown) encircling ,the pivot pin 25 biases the lever 24 into continuous following engagement with the lower edge of the slot so that there is substantially no lost motion between the detent lever and the expansible tube.v

For actuating the switch contact I4 in ref sponse to the movement of the detent lever 24, we provide a switch actuating member 26 pivotally mounted upon an adjustable sleeve 21 and biased by means of a torsion spring 28 for counterclockwise rotation into engagement with the switch contact I4. The switch actuating member 26 is provided with a striker arm 29 positioned to engage the contact I4 for moving the contact to its open circuit position. A reset arm 36 is also mounted upon the actuating member 26 for moving the actuating member from its released or switch opening position back to its latched position. Preferably, both arms 29 and 30 are formed of insulating material. The lower end of the switch actuating member 26 carries a pivotally mounted movable latch 3I which is rotatable through a small angle in a counterclockwise direction with respect to the switch actuating member 26 to permit resetting of the switch actuating member in its latched position.

eccentric pivot arrangement permitting a vernier adjustment of the switch actuating member with respect to the" detent 'lever 24. The adjustable pivot for the member 26 is illustrated in detail in the perspective view of Fig. 4. This mounting comprises an adjustable plate or lever 35 having extending from one side thereof a xed pivot pin 36 for cooperation with a suitable bore in the base plate I pivotally to mount the adjustable plate 35 upon the base plate. The lower end of the plate 35 is slotted radially, as at 31, for cooperation with a clamping bolt 38 in the plate I5 adjustablyto fasten the plate 35 to the base I5 in a desired fixed position. Upon the front surface of adjustable plate 35 there is mounted eccentrically with respect to the pivotpin 36 an adjustable pivot pin 39. The adjustable sleeve 21 is eccentrically bored and rotatably mounted upon the adjustable eccentric pivot pin 39. For adjustably exing the position of the sleeve 21 with respect to the base I5 and thus with respect to any desired iixed position of the pivot pin 39 that the position of the latching dog 32 is deting may be attained by adjustment of the plate 35, and thereafter a line Vernier adjustment may be eilected through proper setting of the eccentric sleeve 21 by means of the attached lever 4I. If desired, the plate 35 may be used as a factory adjustment and its position fixed after an adjusting arm 4I is connected to the sleeve 21.

' be controlled over a wide range by the adjustable plate 35 and over a smaller range within the setting of the plate 35 by means of the eccen-v tric sleeve 21.

Since the detent lever 24 is held in continuousfollowing engagement with the lower end of the thermally expansible tube I9, it will be evident proper setting, while the lever 4I may be left available to the customer for renement of the factory setting. For this purpose the lever 4I is conveniently positioned at the front of the casing.-

In view of the foregoing detailed description of the various parts of our thermal relay and the manner of their assembly, it is believed that the 'mode of operation of the device as a whole will -be evident without detailed explanation. Briey, however, a sustained ow of excessive current through the heater 2l will raise the temperature of the thermally expansible tube I9, thereby causing the tubeA I 9 to expand longitudinally and to move its lower end downward with respect to the base plate I5. Such movement of the lower end ofthe tube I9 permits a clockwise rotation of the detent lever 24 which, if suiiicient, releases the latch 3| and permits the switch actuating lever 26 to rotate in a counterclockwise directionv under the inuence of its biasing spring `28. Movement of the switch actuating lever 26 to its released position brings the striker arm 29 into engagement with the spring contact I4 thereby to move the contact I4 to a circuit inf terrupting position, as illustrated at'Fig. 3. In moving to its released position, the switch actuating member 26 also raises one end of the reset lever 30. The raised end o f the lever 30 is arranged to be engaged by a manually operable reset push button 45. The push button 45 is normally biased to a non-operative position by means of a helical compression spring 46, but may be depressed manually to engage the reset lever 30 and to rotate the switch actuating lever 26 in a clockwise direction to the latched position shown at Fig. 1.

While we have shown only a preferred embodiment of our invention by way of illustration, many other modications will occur to those skilled in the art, and we therefore wish to have it understood that we intend in the appended claims to cover all such modifications as fall within the true spirit and scope of our invention.

What we claim as new and desire to secure by Letters Patent of the United States is:

1. An electric circuit controlling apparatus comprising a pair of cooperating switch contacts, a switch actuating member biased for movement to a released position to effect circuit controlling movement of said contacts, a movable detent member forv normally releasably retaining said switch actuating member `in a latched position against its bias, and means for adjusting the latched position of said switch actuating member with respect to said detent member comprising a laterally adjustable pivot pin and adjustable means rotatably mounted upon said adjustable pivot pin for pivotally supporting said switch actuating member.

2. An electric circuit controlling apparat comprising a pair of cooperating switch contacts,

. a switch actuating member biased for movement to a released position to effect circuit controlling movement of said contacts, a detent member arranged'normally releasably to retain said switch actuating member in a latched position against its bias, thermal responsive means for moving said detent member in accordance with the temperature of said thermal responsive means to release said switch actuating member, and means for adjusting the latched position of said switch actuating member with respect to said detent memberthereby to set said switch actuating member for release at a predetermined temperature of said thermal responsive means comprising an adjustable pivot pin, an adjustable member eccentrically and pivotally mounted upon said pivot pin, and means for pivotally mounting said switch actuating member upon said adjustable member.

3. An electric circuit controlling apparatus comprising a pair of cooperating switch contacts, a switch actuating member biased for movement to a released position to effect circuit controlling movement of said contacts, a movable detent member for normally releasably retaining said switch actuating member in a latched position against its bias, and means for adjusting the latched position of said switch actuating member with respect to said detent member comprising an adjustable pivot pin, an adjustable sleeve eccentrically and rotatably mounted upon said adjustable pivot pin, and means for pivotally mounting said switch actuating member upon said adjustable sleeve.

4. An electric switching apparatus for controlling an electric circuit comprising a pair of cooperating switch contacts, a switch actuating member biased for movement to a released position to effect circuit controlling movement of said contacts,'a, detent member for normally releasably retainingsaid switch actuating member in a latched position against its bias, a thermally responsive member arranged to move said detent member in accordance with the magnitude of current in said circuit, said detent member being connected for continuous following engagement with said thermally responsive member, and means for adjusting the iatched position o! said switch actuating member with respect to said detent member thereby to determine the current value at which said switch actuating member is released by said detent comprising an adjustable plate pivotally mounted at a fixed point, a pivot pin eccentrically mounted upon said adjustable plate, an eccentric sleeve rotatably mounted upon said pivot pin,' means for pivotally mounting said switch actuating member upon said eccentric sleeve, and means for adjustably positioning said sleeve with respect to said pivot pin.

5. A shock-proof electric switching apparatus for controlling' an electric circuit comprising a base, a pair of cooperating switch contacts, a switch actuating member biased for movement to a released position to effect circuit controlling movement of said contacts, a detent member for normally releasably retaining said switch actuating member in a latched position against its bias, a thermally expansible member fixedly mounted at one end upon said base, means for connecting said detent member for continuous following engagement with the movable end of said thermally expansible member, and means for adjusting the latched position of said switch actuating member with respect to said detent member thereby to determine the temperature of said' thermally expansible member at which release of said switch actuating member is effected cornprising a movable plate pivotally mounted and adjustably positionable upon said base, a pivot pin eccentrically mounted upon said movable plate, an eccentric sleeve rotatably mounted upon said pivot pin, means for pivotally mounting said switch actuating member upon said eccentric sleeve, means for adjustably positioning said ec centric sleeve upon said pivot pin, and means for connecting said sleeve to said base in a desired position of adjustment.

6. An electric circuit controlling apparatus comprising a base, a pair of cooperating switch contacts, a switch actuating member biased for movement to a released position to effect circuit controlling movement of said contacts, a movable detent member for normally releasably retaining said switch actuating member in a latched posi- A tion against its bias, means for movably mounting one of said members for predetermined movement with respect to said base, and means for relatively adjustably positioning said switch actuating and detent members in their latched positions comprising an adjustable pivot pin mounted upon said base for lateral movement with respect thereto and adjustable means rotatively mounted upon said adjustable pivot pin for piv` otally supporting the other of said members.

7. An electric circuit controlling apparatus comprising a base, a pair of cooperating switch contacts,u a switch actuating member biased for movement to a released position to eiect circuit controlling movement of said contacts, a detent member.. arranged normally releasably to retain said switch actuating member in a latched position against its bias, thermal responsive means for moving said detent member in continuous Iollowing relation with respect to a thermally movable portion oi' said thermal responsive means, umeans for movably mounting one of said members for predetermined limited movement with respect to said base, and means for relatively adiustably positioning said switch actuating and detent members in their latched positions comprising an adjustable pivot pin movably mounted upon said base, an adiustable sleeve eccentrically and rotatably mounted upon said adjustable pivot pin, and means i'or pivotally mounting the other of said members upon said adjustable sleeve.

GEORGE R. TOWNSEND. CHESTER I. HALL, 

